4-Alkyl-1,4-diaza-5-oxo-cycloheptanes and their 1-oxyls

ABSTRACT

2,2,7,7-Tetraalkyl- and 2,7-dispiroalkylene-5-oxo-1,4-diazacycloheptanes substituted in 4-position by mono- or tetravalent radicals are powerful light-stabilizers for organic polymers. They possess higher compatibility than their 4-unsubstituted homologues, from which they may synthesized by reactions known for N-alkylation. Preferred substituents in 4-position are alkyl, alkylene, alkenyl, aralkyl and esteralkyl groups. The 1-nitroxyls derived from the imidazolidines by oxydation with hydrogen peroxide or percarboxylic acids too are good light stabilizers.

The invention relates to new derivatives of1,4-diaza-5-oxo-cycloheptane, a process for their manufacture, their useas light stabilizers for organic polymers and the polymers stabilisedwith these compounds.

The new compounds correspond to the formula I ##EQU1## wherein R₁, R₂,R₃ and R₄ independently of one another each denote an alkyl group or R₁and R₂ and/or R₃ and R₄ together with the C atom to which they arebonded form a cycloalkane ring, Y denotes hydrogen or the oxyl radicalO.sup.., n denotes an integer from 1 to 4 and X, if n is 1, denotes analkyl group which can be substituted by groups containing O, N or S, analkenyl, alkinyl or aralkyl group or an aralkyl group substituted byhydroxyl or ester groups, if n is 2, an alkylene group which can beinterrupted by O, NH or S or by groups containing O, N or S, or analkenylene, alkinylene or bis(alkylene)arene group, if n is 3, a group##EQU2## IN WHICH M REPRESENTS A NUMBER FROM 1 TO 4 AND T represents atrivalent hydrocarbon radical, and if n is 4, a group ##EQU3## IN WHICHM REPRESENTS A NUMBER FROM 1 TO 4 AND Q represents a tetravalenthydrocarbon radical, and their salts with organic or inorganic acids.

If R₁, R₂, R₃ and R₄ denote an alkyl group, this can be, for example,methyl, ethyl, n-propyl, iso-propyl, tert.-butyl, n-amyl, sec.-amyl,n-octyl, n-decyl, n-dodecyl, n-tetradecyl, n-hexadecyl or n-octadecyl.

If R₁ and R₂, or R₃ and R₄, together with C atom to which they arebonded form a cycloalkyl ring, this can be, for example, a cyclopentyl,cyclohexyl or cyclooctyl ring.

If X denotes alkyl groups, these can be, for example, methyl, ethyl,propyl, iso-propyl, n-butyl, n-hexyl, n-octyl, n-decyl, n-dodecyl orn-octadecyl.

If X is an alkyl group substituted by groups containing O, N or S, X canbe, for example, the following groups: hydroxyalkyl such as --CH₂ CH₂ OHor --CH₂ CHOH--CH₃ ; carboxyalkyl such as --CH₂ COOH; alkyl substitutedby ester groups, for example alkoxycarbonylalkyl such as --CH₂ COOCH₃,--CH₂ COOC₂ H₅, --CH₂ COOC₈ H₁₇, --CH₂ COOC₁₂ H₂₅ or --CH₂ COOC₁₈ H₃₇,or alkylcarbonyloxyalkyl such as --CH₂ CH₂ OOCCH₃, --CH₂ CH₂ OOCC₇ H₁₅,--CH₂ CH₂ OOCC₁₁ H₂₃, --CH₂ CH₂ OOCC₁₇ H₃₅ or ##EQU4## orarylcarbonyloxyalkyl such as ##SPC1##

or cycloalkylcarbonyloxyalkyl such as ##SPC2##

or aralkylcarbonyloxyalkyl such as ##SPC3##

amidoalkyl such as alkylcarbonylaminoalkyl, for example --CH₂ CH₂NHCOCH₃, --CH₂ CH₂ NHCOC₁₇ H₃₅ or --CH₂ CH₂ CH₂ NHCOC₇ H₁₅, orcarbamoylalkyl such as --CH₂ CONH₂ or --CH₂ CH₂ CONH₂, oralkylaminocarbonylalkyl such as --CH₂ CONHC₂ H₅ or --CH₂ CH₂ CONHC₁₂H₂₅, or arylaminocarbonyalkyl such as --CH₂ CH₂ CONHC₆ H₅, ordialkylaminocarbonylalkyl such as --CH₂ CON(CH₃)₂ ; cyanoalkyl, forexample --CH₂ CN or --CH₂ CH₂ CN; alkyl substituted by ether groups,such as alkoxy groups, for example --CH₂ OC₄ H₉ or --CH₂ CH₂ OC₈ H₁₇ ;alkyl substituted by thioether groups, such as alkylthio or arylthiogroups, for example --CH₂ CH₂ SC₈ H₁₇ or ##SPC4##

alkyl substituted by sulphoxide groups, such as alkylsulphinylalkyl, forexample --CH₂ CH₂ SOC₈ H₁₇ ; alkyl substituted by sulphone groups, suchas alkylsulphonylalkyl, for example --CH₂ CH₂ CH₂ SO₂ C₁₂ H₂₅ ;aminoalkyl, such as aminoalkyl unsubstituted at the nitrogen atom, forexample --CH₂ CH₂ NH₂ or --CH₂ CH₂ CH₂ NH₂, or such as aminoalkylsubstituted by alkyl at the nitrogen atom, for example --CH₂ CH₂--N(CH₃)₂, --CH₂ CH₂ CH₂ N(C₂ H₅)₂ or --CH₂ CH₂ NHCH₂ CH₂ CN.

If X denotes alkenyl it can be, for example, propenyl, butenyl,pentenyl, hexenyl, octenyl, decenyl, tetradecenyl or octadecenyl.

If X denotes alkinyl, it can be, for example, propargyl.

If X is unsubstituted aralkyl, it can be benzyl, α-phenylethyl orα,α-dimethylbenzyl.

If X is an aralkyl radical substituted by hydroxyl or ester groups, itcan be, for example, 3,5-di-tert.-butyl-4-hydroxybenzyl,4-propionoxybenzyl or 4-ethoxycarbonylbenzyl.

If X (in the case that n = 2) represents an alkylene radical, it can be,for example, methylene, ethylene, trimethylene, tetramethylene,pentamethylene, hexamethylene, heptamethylene, octamethylene,nonamethylene, decamethylene or octadecamethylene.

If the alkylene radical is interrupted by O, NH or S or by groupscontaining O, N or S, it can be, for example, the following alkyleneradicals: radicals interrupted by O or S, such as --(CH₂)₂ --O--(CH₂)₂--, --(CH₂)₂ --S--(CH₂)₂ --, --CH₂ CH₂ S(CH₂)₂ SCH₂ CH₂ --, --CH₂ CH₂S(CH₂)₃ SCH₂ CH₂ --, --CH₂ CH₂ S(CH₂)₄ SCH₂ CH₂ --, --CH₂ CH₂ S(CH₂)₈SCH₂ CH₂ -- or --CH₂ CH₂ S(CH₂)₁₂ SCH₂ CH₂ --; radicals interrupted byNH or amino groups, such as ##EQU5## alkylene radicals interrupted byester groups, such as ##EQU6## alkylene radicals interrupted by amidegroups, such as --CH₂ CONH(CH₂)₂ NHCO--CH₂ --, --CH₂ CONH(CH₂)₆ NHCOCH₂--, --CH₂ CONH(CH₂)₁₂ NHCOCH₂ --, --(CH₂)₂ CONH(CH₂)₄ NHCO(CH₂)₂ --,--(CH₂)₂ CONH(CH₂)₆ NHCO(CH₂)₂ --, --(CH₂)₂ CONH(CH₂)₈ NHCO(CH₂)₂ -- or--(CH₂)₃ CONH(CH₂).sub. 2 NHCO(CH₂)₃ --; radicals interrupted bysulphoxide groups, such as --(CH₂)₂ --SO--(CH₂)₂ --, --CH₂ CH₂ --SO--CH₂CH₂ --SO--CH₂ CH₂ --, --(CH₂)₂ --SO--(CH₂)₁₂ --SO--(CH₂)₂ -- or ##EQU7##radicals interrupted by sulphone groups such as CH₂ --CH₂ --SO₂ --CH₂--CH₂ --, --CH₂ CH₂ --SO₂ --(CH₂)₆ --SO₂ --CH₂ CH₂ --, ##EQU8##

If X denotes alkenylene or alkinylene, it can be, for example,2-butenylene-1,4, 2-butinylene-1,4 or 2,4-hexadiinylene-1,6.

If X denotes bis(alkylene)arene, it can be 1,2-bis-(methylene)-benzene,1,3-bis-(methylene)-benzene, 1,4-bis-(methylene)-benzene,1,2-bis-(ethylene)-benzene, 1,3-bis-(ethylene)-benzene,1,4-bis-(ethylene)-benzene or 4,4'-bis-(methylene)-diphenyl.

The trivalent hydrocarbon radical T can be, for example, one of thefollowing radicals: ##EQU9##

The tetravalent hydrocarbon radical Q can be, for example, the radical##EQU10##

The salts of the compounds of the formula I with organic or inorganicacids can be, for example, salts of acetic acid, formic acid, tartaricacid, phenylphosphonic acid, maleic acid, phosphoric acid, hydrochloricacid, phosphorous acid or carbonic acid.

Preferred compounds of the formula I are those wherein R₁, R₂, R₃ and R₄independently of one another denote alkyl with 1 to 8 C atoms or R₁ andR₂ and/or R₃ and R₄ together with the C atom to which they are bondedform a cyclopentyl or cyclohexyl ring, Y denotes --H or the oxyl radical--O.sup.., n denotes an integer from 1 to 4 and X, if n is 1, denotesalkyl with 1 to 20 C atoms which can be substituted by hydroxyl,carboxyl, ester, amide, nitrile, ether, thioether, sulphoxide, sulphoneor amino groups, alkenyl or alkinyl with 3 to 18 C atoms or aralkyl with7 to 15 C atoms, which can be substituted by hydroxyl or ester groups,if n is 2, alkylene with 1 to 12 C atoms, alkylene with 2 to 20 C atomswhich is interrupted by ether, ester, thioether, amide, sulphoxide,sulphone or amino groups, alkenylene or alkinylene with 4 to 20 C atomsor bis(alkylene)arene with 8 to 14 C atoms, if n = 3, a group ##EQU11##in which m represents a number from 1 to 3 and T represents a trivalentaliphatic hydrocarbon radical with 3 to 7 C atoms and if n = 4, a group##EQU12## in which m represents a number from 1 to 3 and Q a tetravalentaliphatic hydrocarbon radical with 4 or 5 C atoms, as well as theirsalts with carboxylic acids or organophosphorus acids with 1 to 20 Catoms.

Compounds of particular interest are those of the formula I wherein R₁,R₂, R₃ and R₄ denote alkyl with 1 to 4 C atoms or R₁ and R₂ and R₃ andR₄ together with the C atom to which they are bonded form a cyclohexylring, Y denotes --H or the oxyl radical --O.sup.., n denotes a numberfrom 1 to 4 and X, if n = 1, denotes alkyl with 1 to 18 C atoms, whichcan be substituted by hydroxyl, carboxyl, ester, amide, nitrile, ether,thioether, sulphoxide, sulphone or amino groups, alkenyl or alkinyl with3 to 5 C atoms, benzyl or benzyl which is substituted by hydroxyl orester groups, if n = 2, alkylene with 1 to 8 C atoms, alkylene with 2 to12 C atoms which is interrupted by ether, ester, thioether, sulphoxide,sulphone or amino groups, alkenylene or alkinylene with 4 to 6 C atomsor xylylene, if n = 3, a group ##EQU13## in which m represents a numberfrom 1 to 3 and T represents a trivalent aliphatic hydrocarbon radicalwith 3 to 5 C atoms and if n = 4, a group ##EQU14## in which mrepresents a number from 1 to 3 and Q represents a tetravalent aliphatichydrocarbon radical with 4 or 5 C atoms, in particular compounds of theformula I, wherein R₁, R₂, R₃ and R₄ denote methyl, Y denotes --H or theoxyl radical --O.sup.., n denotes the number 1 or 2 and X, if n is 1,denotes alkyl with 1 to 18 C atoms which can be substituted by estergroups, allyl, methallyl, propargyl or benzyl, and if n is 2, denotesalkylene with 2 to 4 C atoms or alkylene with 6-10 C atoms which isinterrupted by ester groups.

Examples of specific compounds of the formula I are:4-(2'-phenyl-2'-hydroxyethyl)-2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptane,4-(carboxymethyl)-2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptane,4-(octyloxycarbonylmethyl)-2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptane,4-(octadecyloxycarbonymethyl)-2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptane,4-(methoxycarbonylethyl)-2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptane,4-(ethoxycarbonylethyl)-2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptane,4-(octyloxycarbonylethyl)-2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptane,4-(octadecyloxycarbonylethyl)-2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptane,4-(2'-phenyl-2'-acetoxyethyl)-2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptane,4-(acetamido-ethyl)-2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptane,4-(cyanomethyl)-2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptane,4-(octyloxyethyl)-2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptane,4-(octylthioethyl)-2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptane,4-(octylsulphinylethyl)-2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptane,4-(octylsulphonylethyl)-2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptane,4-(allyl)-2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptane,4-(methallyl)-2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptane,4-(propargyl)-2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptane,4-(benzyl)-2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptan-1-oxyl,1',2'-bis(2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptyl-4)-ethane,1',8'-bis(2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptyl-4)-n-octane,ethylene-di-(2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptyl-4)-acetate,1',4'-butylene-di(2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptyl-4)-acetate,1',8'-octylene-di(2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptyl-4)-acetate,1',18'-octadecylene-di(2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptyl-4)-acetate,ethylene-di-β-(2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptyl-4)-propionate,1',4'-butylene-di-γ-(2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptyl-4)-butyrate,N,N'-ethylene-bis[(2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptyl-4)-acetamide],1',6'-N,N'-hexamethylene-bis[(2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptyl-4)-acetamide],1',4'-bis(2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptyl-4)-butene-2',1',4'-bis(2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptyl-4)-butine-2',bis(2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptyl-4)-o-xylylene,bis(2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptyl-4)-m-xylylene,bis(2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptyl-4 )-p-xylylene,tris(2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptyl-4-acetoxy)-propane-1',2',3',tris-(2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptyl-4-propionoxy)-propane-1',2',3',tris-(2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptyl-4-acetoxymethyl)-ethane-1',1',1',tetrakis(2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptyl-4-propionoxymethyl)-methane,15-butyl-7,15-diaza-16-oxo-dispiro[5.1.5.4]heptadecane,15-octyl-7,15-diaza-16-oxo-dispiro[5.1.5.4]heptadecane,15-octadecyl-7,15-diaza-16-oxo-dispiro[5.1.5.4]heptadecane,15-(2'-phenyl-2'-hydroxyethyl)-7,15-diaza-16-oxo-dispiro[5.1.5.4]heptadecane,15-carboxymethyl-7,15-diaza-16-oxo-dispiro[5.1.5.4]heptadecane,15-butyloxycarbonylmethyl-7,15-diaza-16-oxo-di-spiro[5.1.5.4]heptadecane,15-octyloxycarbonylmethyl-7,15-diaza-16-oxo-dispiro[5.1.5.4]heptadecane,15-ethoxycarbonylethyl-7,15-diaza-16 -oxo-dispiro[5.1.5.4]heptadecane,15-octyloxycarbonylethyl-7,15-diaza- 16-oxo-dispiro[5.1.5.4]heptadecane,15-(2'-phenyl-2'-acetoxy-ethyl)-7,15-diaza-16-oxo-dispiro[5.1.5.4]heptadecane,15-cyanoethyl-7,15-diaza-16-oxo-dispiro[5.1.5.4]heptadecane,15-allyl-7,15-diaza-16-oxo-dispiro[5.1.5.4]heptadecane,15-benzyl-7,15-diaza- 16-oxo-dispiro[5.1.5.4]heptadecane,1',2'-bis(7,15-diaza-16-oxo-dispiro[5.1.5.4]heptadecyl-15)-ethane,1',4'-bis(7,15-diaza-16-oxo-dispiro[5.1.5.4]heptadecyl-15)-n-butane,1',8'-bis(7,15-diaza-16-oxo-dispiro[5.1.5.4]heptadecyl-15)-n-octane,ethylene-di(7,15-diaza-16-oxo-dispiro[5.1.5.4]heptadecyl-15)-acetate,1',8'-octylene-di(7,15-diaza-16-oxo-dispiro[5.1.5.4]heptadecyl-15)-acetate,N,N'-ethylene-bis[(7,15-diaza-16-oxo-dispiro[5.1.5.4]heptadecyl-15)-acetamide],N,N'-hexamethylene-bis[(7,15-diaza-16-oxodispiro[5.1.5.4]heptadecyl-15)-acetamide],1',4'-bis(7,15-diaza-16-oxo-dispiro[5.1.5.4]heptadecyl-15)-2'-butene,1',4'-bis(7,15-diaza-16-oxo-dispiro[5.1.5.4]heptadecyl-15)-2'-butine,bis(7,15-diaza-16-oxo-dispiro[5.1.5.4]heptadecyl-15)-o-xylylene,bis(7,15-diaza-16-oxo-dispiro[5.1.5.4]heptadecyl-15)-p-xylylene,tris(7,15-diaza-16-oxo-dispiro[5.1.5.4]heptadecyl-15-acetoxy)propane-1',2',3',tris(7,15-diaza-16-oxo-dispiro[5.1.5.4]heptadecyl-15-acetoxymethyl)-ethane-1',1',1' and tetrakis(7,15-diaza-16-oxo-dispiro[5.1.5.4]heptadecyl-15-acetoxymethyl)-methane.

The compounds according to the invention, of the formula I, can bemanufactured by reacting 5-oxo-1,4-diazacycloheptanes of the formula II##EQU15## in which R₁, R₂, R₃ and R₄ independently of one another eachdenote an alkyl group or R₁ and R₂ and/or R₃ and R₄ together with the Catom to which they are bonded form a cycloalkane ring, with alkylatingagents and optionally a) oxidising the compounds of the formula I, thusobtained, wherein Y is hydrogen, to compounds of the formula I in whichY represents the oxyl radical, or optionally b) converting compounds ofthe formula I thus obtained, wherein Y is hydrogen, into thecorresponding salts by treatment with organic or inorganic acids.

The 5-oxo-1,4-diazacycloheptanes of the formula II used as the startingmaterial are known substances which can be manufactured, for example, inaccordance with the process described in Journal of Org. Chem. 14, 530(1949), by reaction of the corresponding piperidones with hydrazoic acidor by Beckmann rearrangement of the piperidone-oximes.

Examples of such compounds of the formula II which are suitable for useas the starting material are:2,2,7,7-tetramethyl-5-oxo-1,4-diazacycloheptane,2,2,7,7-tetraisopropyl-5-oxo-1,4-diazacycloheptane,2,7-dimethyl-2,7-diisopropyl-5-oxo-1,4-diazacycloheptane,7,15-diaza-16-oxo-dispiro[5.1.5.4]heptadecane,6,13-diaza-14-oxo-dispiro[4.1.4.4]pentadecane and8,8-dimethyl-11-oxo-7,10-diazaspiro[5.6]dodecane.

The conversion of the diazacycloheptanones of the formula II to thecompounds of the formula I, wherein Y is hydrogen, is carried outaccording to known methods of alkylation, with known alkylating agents.

The most versatile method is the reaction with organic halogen compoundsof the formula X-Hal_(n), wherein Hal denotes chlorine, bromine oriodine and X and n have the abovementioned meaning, in the presence ofmolar amounts of a deprotonising agent, or after deprotonising thestarting compound of the formula II with such a deprotonising agent. Asthe latter it is possible to use all known deprotonising agents, butespecially alkali metals, alkali metal hydrides, alkaline earth metalhydrides, alkali metal amides or alkali metal alcoholates.

As examples of organic halogen compounds X-Hal_(n) which can be usedaccording to the invention there may be mentioned: methyl iodide, ethylbromide, n-propyl bromide, 1-n-dodecyl bromide, ethylene chlorohydrin,propionic acid chloroethyl ester, hexahydrobenzoic acid 2-chloroethylester, chloroacetic acid, sodium chloroacetate, ethyl chloroacetate,chloroacetamide, N-dimethylchloroacetamide, chloroacetanilide,chloroacetonitrile, 1-β-chloroethoxy-n-octane,1-β-bromoethylmercaptobutane, allyl chloride, oleyl bromide, propargylchloride, benzyl chloride, β-phenylethyl bromide,3,5-di-tert.-butyl-4-hydroxybenzyl chloride, 4-chloromethyl-benzoic acidethyl ester, 1,2-dibromoethane, tetramethlene dibromide, dodecamethylenediiodide, 2,2'-dichlorodiethyl ether, ethylene glycol bis-(2-chloroethylether), bis-(2-chloroethyl)-2-cyanoethylamine, ethylenedi(chloroacetate), hexamethylene di(bromoacetate), adipic aciddi(2-chloroethyl ester), diglycollic acid di(2-chloroethyl ester),thiopropionic acid di(2-chloroethyl ester), sulphonedipropionic aciddi(2-chloroethyl ester), hexamethylene-bis(chloroacetamide),1,4-dichlorobutene-2, 1,4-dichlorobutine-2, 1,6-dichlorohexadiine-2,4,o-, m- or p-xylylene dichloride, glycerine tri(chloroactate),trimethylolpropane tri(chloroacetate) and pentaerythritoltetra(chloroacetate).

The reaction is preferably carried out in organic solvents such as, forexample, in benzene, toluene, dimethylformamide, dimethylsulphoxide ortheir mixtures.

The hydroxyalkylation of the diazacycloheptanones with formaldehydegives hydroxymethyl compounds whilst with epoxides it gives2-hydroxyalkyl compounds. Examples of such epoxides are ethylene oxide,propylene oxide or styrene oxide.

If the reaction with formaldehyde is carried out in the presence of analcohol, the corresponding alkoxymethyl derivatives are formed; forexample, the N-butoxymethyl derivative is formed in the presence ofbutanol.

One method of alkylation for the introduction of aminoalkyl groupsconsists of the reaction of the diazacycloheptanones with formaldehydeand amines or their salts, preferably with secondary amines such as, forexample, dimethylamine, diethylamine or their salts.

A further important method for the introduction of substituted alkylgroups is the base-catalysed addition of α,β-unsaturated carboxylic acidderivatives, above all of acrylonitrile, acrylic acid esters andacrylamide. Vinylsulphones and vinylsulphoxides, for examplevinyl-benzylsulphone or divinylsulphone can also be added on under theseconditions.

Some of the substituted diazacycloheptanone derivatives obtained by suchalkylation reactions can be converted into other compounds of theformula I with Y = H according to known methods, by a further reactionstage. Thus, for example, the 3-cyanoethyl derivatives can be convertedinto the 3-aminopropyl derivatives by hydrogenation. The hydroxyalkylcompounds can be esterified to the acyloxyalkyl compounds withcarboxylic acids. Thioether compounds can be oxidised to the sulphoxidesor the sulphones and ester compounds can be hydrolysed to the freecarboxyl compounds.

The diazacycloheptanone compounds of the formula I, thus obtainable,which are substituted in the 5-position and in which Y = H, can beconverted into the corresponding nitroxyls of the formula I, in which Yrepresents the oxyl radical. This takes place according to knownmethods, for example by oxidation with hydrogen peroxide and sodiumtungstate in an aqueous medium or by oxidation with percarboxylic acidsuch as, for example, peracetic acid or m-chloroperbenzoic acid inorganic solvents.

Since the diazacycloheptanone derivatives according to the invention arebasic compounds, they are able to form salts with organic or inorganicacids. The salt formation takes place according to known methods byaddition of the corresponding acid in stoichiometric amounts or inexcess amounts, during or after the manufacture of the compounds of theformula I. Acids which are suitable for this purpose are, for example,acetic acid, formic acid, tartaric acid, phenylphosphonic acid, maleicacid or phosphoric acid.

The physical properties of the compounds according to the invention, ofthe formula I, differ greatly depending on the individual substituents,above all depending on the substituent X. However, all compounds of theformula I, when added even in small amounts, protect organic polymersagainst aging through the action of light.

The light aging of organic polymers can on the one hand lead todegradation and deterioration of the mechanical properties, associatedtherewith, and, on the other hand, to a discolouration of the polymers.Both aging phenomena can also occur alongside one another. The compoundsaccording to the invention now protect organic polymers against both theadverse phenomena of light aging and, surprisingly, do so substantiallymore effectively than the known starting compounds of the formula II areable to do.

Polymers of which the light aging can be delayed or prevented by thecompounds of the formula I according to the invention are, for example,the following categories which are industrially important.

1. Polymers which are derived from singly or doubly unsaturatedhydrocarbons such as, for example, polyolefines such as polyethylene,which can optionally be crosslinked, polypropylene, polybutene-1,polyisobutene, polymethylbutene-1, polymethylpentene-1, polyisoprene,polybutadiene, polystyrene, copolymers of the monomers on which thehomopolymers mentioned are based, such as ethylene-propylene copolymers,propylene-butene-1 copolymers, propylene-isobutene copolymers,styrene-butadiene copolymers and terpolymers of ethylene and propylenewith a diene such as, for example, hexadiene, dicyclopentadiene orethylidenenorbornene; mixtures of the abovementioned homopolymers suchas, for example, mixtures of polypropylene and polyethylene,polypropylene and polybutene-1 or polypropylene and polyisobutylene, orof butadieneacrylonitrile copolymer with a styrene-butadiene copolymer.

2. Vinyl polymers containing halogen such as polyvinyl chloride,polyvinylidene chloride, polyvinyl fluoride, polychloroprene andchlorinated rubbers.

3. Polymers which are derived from α,β-unsaturated acids and theirderivatives, such as polyacrylates and polymethacrylates,polyacrylamides and polyacrylonitrile, as well as their copolymers withother vinyl compounds, such as acrylonitrile/butadiene/styrene,acrylonitrile/styrene and acrylonitrile/styrene/acrylic estercopolymers.

4. Polymers which are derived from unsaturated alcohols and amines ortheir acyl derivatives or acetals, such as polyvinyl alcohol, polyvinylacetate, stearate, benzoate and maleate, polyvinyl butyral, polyallylphthalate, polyallylmelamine and their copolymers with other vinylcompounds such as ethylene/vinyl acetate copolymers.

5. Homopolymers and copolymers which are derived from epoxides, such aspolyethylene oxide or the polymers which are derived from bis-glycidylethers.

6. Polyacetals, such as polyoxymethylene and polyoxyethylene, as well aspolyoxymethylenes which contain ethylene oxide as a comonomer.

7. Polyphenylene oxides.

8. Polyurethanes and polyureas.

8. Polycarbonates.

10. Polysulphones.

11. Polyamides and copolyamides which are derived from diamines anddicarboxylic acids and/or from aminocarboxylic acids or thecorresponding lactams, such as polyamide 6, polyamide 6/6, polyamide6/10, polyamide 11 and polyamide 12.

12. Polyesters which are derived from dicarboxylic acids and dialcoholsand/or from hydroxycarboxylic acids or the corresponding lactones, suchas polyethylene glycol terephthalate, polybutylene terephthalate,poly-1,4-dimethylol-cyclohexane terephthalate and their startingmaterials, such as lower terephthalic acid alkyl esters.

13. Crosslinked polymers which are derived from aldehydes, on the onehand, and phenols, ureas and melamines, on the other, such asphenol-formaldehyde, urea-formaldehyde and melamine-formaldehyde resins.

14. Alkyd resins, such as glycerine-phthalic acid resins and theirmixtures with melamine-formaldehyde resins.

15. Unsaturated polyester resins which are derived from copolyesters ofsaturated and unsaturated dicarboxylic acids with polyhydric alcohols,and vinyl compounds as crosslinking agents, and also theirhalogen-containing modifications of low flammability.

16. Natural polymers, such as cellulose, rubber, proteins, and theirpolymer-homologously chemically modified derivatives, such as celluloseacetates, propionates and butyrates, or the cellulose ethers, such asmethylcellulose.

Preferred polymers are polyethylene of high and low density,polypropylene, polybutadiene, polyvinyl chloride, polystyrene and itscopolymers and mixtures thereof.

The new compounds are added to the substrates in a concentration of 0.01to 5% by weight, calculated relative to the material to be stabilised.Preferably, 0.05 to 1.5, and especially preferentially 0.1 to 0.8, % byweight of the compounds, calculated relative to the material to bestabilised, are incorporated into the latter.

The incorporation can be effected after the polymerisation, for exampleby mixing the compounds and optionally further additives into the meltin accordance with the industrially customary methods, before or aftershaping, or by applying the dissolved or dispersed compounds to thepolymer, if necessary with subsequent evaporation of the solvent.

The new compounds can also be added to the polymers to be stabilised inthe form of a master batch which contains these compounds, for example,in a concentration of 2.5 to 25% by weight.

In the case of crosslinked polyethylene, the compounds are added beforecrosslinking.

The following may be mentioned as further additives together with whichthe stabilisers usable according to the invention can be employed:

1. Antioxidants

1.1 Simple 2.6-dialkylphenols such as, for example,2,6-di-tert.-butyl-4-methylphenol, 2-tert.-butyl-4,6-dimethylphenol,2,6-di-tert.-butyl-4-methoxymethylphenol and2,6-dioctadecyl-4-methylphenol.

1.2 Derivatives of alkylated hydroquinones such as, for example,2,5-di-tert.-butyl-hydroquinone, 2,5-di-tert.-amylhydroquinone,2,6-di-tert.-butyl-hydroquinone, 2,5-di-tert.-butyl-4-hydroxy-anisole,3,5-di-tert,-butyl-4-hydroxy-anisole,tris-(3,5-di-tert.-butyl-4-hydroxyphenyl)-phosphite,3,5-di-tert.-butyl-4-hydroxyphenol-stearate andbis-(3,5-di-tert.-butyl-4-hydroxyphenyl)-adipate.

1.3 Hydroxylated thiodiphenyl ethers such as, for example,2,2'-thio-bis-(6-tert.-butyl-4-methylphenol),2,2'-thio-bis-(4-octylphenol),4,4'-thio-bis-(6-tert.-butyl-3-methylphenol),4,4'-thio-bis-(3,6-di-sec.-amylphenol),4,4'-thio-bis-(6-tert.-butyl-2-methylphenol) and4,4'-bis-(2,6-dimethyl-4-hydroxyphenyl)-disulphide.

1.4 Alkylidene-bisphenols such as, for example,2,2'-methylene-bis-(6-tert.butyl-4-methylphenol),2,2'-methylene-bis-(6-tert.butyl-4-ethylphenol),4,4'-methylene-bis-(6-tert.butyl-2-methylphenol),4,4'-methylene-bis-(2,6-di-tert.butyl-phenol),2,6-di-(3-tert.butyl-5-methyl-2-hydroxybenzyl)-4-methylphenol,2,2'-methylene-bis-[4-methyl-6-(α-methylcyclohexyl)-phenol],1,1-bis-(3,5-dimethyl-2-hydroxyphenyl)butane,1,1-bis-(5-tert.butyl-4-hydroxy-2-methylphenyl)-butane,2,2-bis-(5-tert.butyl-4-hydroxy-2-methylphenyl)-butane,2,2-bis-(3,5-di-tert.butyl-4-hydroxyphenyl)-propane,1,1,3-tris-(5-tert.butyl-4-hydroxy-2-methylphenyl)-butane,2,2-bis-(5-tert.butyl-4-hydroxy-2-methylphenyl)-4-n-dodecylmercapto-butane,1,1,5,5-tetra-(5-tert.butyl-4-hydroxy-2-methylphenyl)-pentane andethylene-glycol-bis-[3,3-bis-(3'-tert.butyl-4'-hydroxyphenyl)-butyrate].

1.5 O-, N- and S-benzyl compounds such as, for example,3,5,3',5'-tetra-tert.butyl-4,4'-dihydroxydibenzyl ether,4-hydroxy-3,5-dimethylbenzyl-mercaptoacetic acid octadecyl ester,tri-(3,5-di-tert.butyl-4-hydroxybenzyl)-amine andbis-(4-tert.butyl-3-hydroxy-2,6-dimethylbenzyl)-dithiol terephthalate.

1.6 Hydroxybenzylated malonic esters such as, for example,2,2-bis-3,5-di-tert.butyl-2-hydroxybenzyl)-malonic acid dioctadecylester, 2-(3-tert.butyl-4-hydroxy-5-methylbenzyl)-malonic aciddioctadecyl ester, 2,2-bis-(3,5-di-tert.butyl-4-hydroxybenzyl)-malonicacid di-dodecylmercapto ethylester and2,2-bis-(3,5-di-tert.butyl-4-hydroxybenzyl)-malonic aciddi-[4-(1,1,3,3-tetramethylbutyl)-phenyl]-ester.

1.7 Hydroxybenzyl-aromatics such as, for example,1,3,5-tri-(3,5-di-tert.butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene,1,4-di-(3,5-di-tert.butyl-4-hydroxybenzyl)-2,3,5,6-tetramethylbenzeneand 2,4,6-tri-(3,5-di-tert.butyl-4-hydroxybenzyl)-phenol.

1.8 s-Triazine compounds such as, for example,2,4-bis-octylmercapto-6-(3,5-di-tert.butyl-4-hydroxy-anilino)-s-triazine,2-octylmercapto-4,6-bis-(3,5-di-tert.butyl-4-hydroxy-anilino)-s-triazine,2-octylmercapto-4,6-bis-(3,5-di-tert.butyl-4-hydroxy-phenoxy)-s-triazine,2,4,6-tris-(3,5-di-tert.butyl-4-hydroxyphenoxy)-s-triazine,2,4,6-tris-(3,5-di-tert.butyl-4-hydroxyphenylethyl)-s-triazine and1,3,5-tris-(3,5-di-tert.butyl-4-hydroxybenzyl)-isocyanurate.

1.9 Amides of β-(3,5-di-tert.butyl-4-hydroxyphenyl)-propionic acid, suchas, for example,1,3,3-tri-(3,5-di-tert.butyl-4-hydroxyphenyl-propionyl)-hexahydro-s-triazineandN,N'-di-(3,5-di-tert.butyl-4-hydroxyphenyl-propionyl)-hexamethylenediamine.

1.10. Esters of β-(3,5-di-tert.butyl-4-hydroxyphenyl)-propionic acidwith monohydric or polyhydric alcohols, such as, for example, methanol,ethanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, etylene glycol,1,2-propanediol, diethylene glycol, thiodiethylene glycol, neopentylglycol, pentaerythritol, 3-thia-undecanol, 3-thia-pentadecanol,trimethylhexanediol, trimethylolethane, trimethylolpropane,trishydroxyethyl-isocyanurate and4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2,2,2]octane.

1.11. Esters of β-(5-tert.butyl-4-hydroxy-3-methylphenylpropionic acidwith monohydric or polyhydric alcohols such as, for example, methanol,ethanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol,1,2-propanediol, diethylene glycol, thiodiethylene glycol, neopentylglycol, pentaerythritol, 3-thia-undecanol, 3-thia-pentadecanol,trimethylhexanediol, trimethylolethane, trimethylolpropane,tris-hydroxyethylisocyanurate and4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2,2,2]octane.

1.12. Esters of 3,5-ditert.butyl-4-hydroxyphenylacetic acid withmonohydric or polyhydric alcohols such as, for example, methanol,ethanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol,1,2-propanediol, diethylene glycol, thiodiethylene glycol, neopentylglycol, pentaerythritol, 3-thia-undecanol, 3-thia-pentadecanol,trimethylhexanediol, trimethylolethane, trimethylolpropane,tris-hydroxyethylisocyanurate and4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo [2,2,2]octane.

1.13. Acylaminophenols such as, for example,N-(3,5-di-tert.butyl-4-hydroxyphenyl)-stearic acid amide andN,N'-di-(3,5-ditert.butyl-4-hydroxyphenyl)-thiobis-acetamide.

1.14. Benzylphosphonates such as, for example,3,5-di-tert.butyl-4-hydroxybenzyl-phosphonic acid dimethyl ester,3,5-di-tert.butyl-4-hydroxybenzyl-phosphonic acid diethyl ester,3,5-di-tert.butyl-4-hydroxybenzyl-phosphonic acid dioctadecyl ester and5-tert.butyl-4-hydroxy-3-methylbenzyl-phosphonic acid dioctadecyl ester.

1.15. Aminoaryl derivatives, such as, for example,phenyl-1-naphthylamine, phenyl-2-naphthylamine,N,N'-diphenyl-p-phenylenediamine, N,N'-di-2-naphthyl-p-phenylenediamine,N,N'-di-sec.butyl-p-phenylenediamine,6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline,6-dodecyl-2,2,4-trimethyl-1,2-dihydroquinoline, monooctyliminodibenzyland dioctyliminodibenzyl and polymerised2,2,4-trimethyl-1,2-dihydroquinoline.

2. UV absorbers and light protection agents

2.1. 2-(2'-Hydroxyphenyl)-benztriazoles, such as, for example, the5'-methyl-, 3',5'-di-tert.butyl-, 5'-tert.butyl-,5'-(1,1,3,3-tetramethylbutyl)-, 5-chloro-3',5'-di-tert.butyl-,5-chloro-3'-tert.butyl-5'-methyl-, 3'-sec.butyl-5'-tert.butyl-,3'-α-methyl-benzyl-5'-methyl-, 3'-α-methylbenzyl-5'-methyl-5-chloro-,4-hydroxy-, 4'-methoxy-, 4'-octoxy-, 3',5'-di-tert.amyl-,3'-methyl-5'-carbomethoxyethyl- and 5-chloro-3',5'-di-tert.amyl-derivative.

2.2. 2,4-Bis-(2'-hydroxyphenyl)-6-alkyl-s-triazines, such as, forexample, the 6-ethyl-, 6-heptadecyl or 6-undecyl-derivative.

2.3. 2-Hydroxy-benzophenones, such as, for example, the 4-hydroxy-,4-methoxy-, 4-octoxy, 4-decyloxy-, 4-dodecyloxy-, 4-benzyloxy,4,2',4'-trihydroxy- or 2'-hydroxy-4,4'-dimethoxyderivative.

2.4. 1,3-Bis-(2'-hydroxy-benzoyl)-benzenes, such as, for example,1,3-bis-(2'-hydroxy-4'-hexyloxy-benzoyl)-benzene,1,3-bis-(2'-hydroxy-4'octyloxy-benzoyl)-benzene and1,3-bis-(2'-hydroxy-4'-dodecyloxy-benzoyl)-benzene.

2.5. Esters of optionally substituted benzoic acids such as, forexample, phenyl salicylate, octylphenyl salicylate,di-benzoylresorcinol, bis-(4-tert.butylbenzoyl)-resorcinol,benzoylresorcinol and 3,5-di-tert.butyl-4-hydroxybenzoic acid2,4-di-tert.butyl-phenyl ester, octadecyl ester or2-methyl-4,6-di-tert.butyl-phenyl ester.

2.6. Acrylates, such as, for example, α-cyano-β,β-diphenylacrylic acidethyl ester or isooctyl ester, α-carbomethoxy-cinnamic acid methylester, α-cyano-β-methyl-p-methoxy-cinnamic acid methyl ester or butylester and N-(β-carbomethoxy-vinyl)-2-methyl-indoline.

2.7. Nickel compounds, such as, for example, nickel complexes of2,2'-thio-bis-[4-(1,1,3,3-tetramethylbutyl)-phenol], such as the 1:1 or1:2 complex, optionally with additional ligands such as n-butylamine,triethanolamine or N-cyclohexyl-di-ethanolamine, nickel complexes ofbis-[2-hydroxy-4-(1,1,3,3-tetramethylbutyl)-phenyl]-sulphone, such asthe 2:1 complex, optionally with additional ligands such as2-ethyl-caproic acid, nickel dibutyldithiocarbamate, nickel salts of4-hydroxy-3,5-di-tert.butylbenzyl-phosphonic acid monoalkyl esters, suchas the methyl, ethyl or butyl ester, the nickel complexes of ketoximessuch as of 2-hydroxy-4-methyl-phenyl-undecylketonoxime and nickel3,5-di-tert.butyl-4-hydroxy-benzoate.

2.8. Sterically hindered amines, such as, for example,4-benzoyloxy-2,2,6,6-tetramethylpiperidine,4-stearoyloxy-2,2,6,6-tetramethylpiperidine,bis-(2,2,6,6-tetramethylpiperidyl)-sebacate, and3-n-octyl-7,7,9,9-tetramethyl-1,3,8-triaza-spiro[4,5]decane-2,4-dione.

2.9. Oxalic acid diamides, such as, for example,4,4'-di-octyloxy-oxanilide,2,2'-di-octyloxy-5,5'-di-tert.butyl-oxanilide,2,2'-di-dodecyloxy-5,5'-di-tert.butyl-oxanilide,2-ethoxy-2'-ethyl-oxanilide, N,N'-bis-(3-dimethylaminopropyl)-oxalamide,2-ethoxy-5-tert.butyl-2'-ethyl-oxanilide and its mixture with2-ethoxy-2'-ethyl-5,4'-di-tert. butyl-oxanilide, mixtures of ortho- andpara-methoxy- as well as of o- and p-ethoxydisubstituted oxanilides.

3. Metal deactivators, such as, for example, oxanilide, isophthalic aciddihydrazide, sebacic acid bis-phenylhydrazide, bis-benzylidene-oxalicacid dihydrazide, N,N'-diacetyl-adipic acid dihydrazide,N,N'-bis-salicyloyloxalic acid dihydrazide,N,N'-bis-salicyloyl-hydrazine andN,N'-bis-(3,5-di-tert.butyl-4-hydroxyphenyl-propionyl)hydrazine.

4. Phosphites, such as, for example, triphenylphosphite,diphenylalkylphosphites, phenyldialkylphosphites,tri-(nonylphenyl)-phosphite, trilaurylphosphite, trioctadecylphosphite,3,9-di-isodecyloxy-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5] undecaneand tri-(4-hydroxy-3,5-di-tert.butylphenyl)-phosphite.

5. Compounds which destroy peroxides, such as, for example, esters ofβ-thiodipropionic acid, for example the lauryl, stearyl, myrystyl ortridecyl esters, salts of 2-mercaptobenzimidazole, for example the Znsalt, and diphenylthiourea.

6. Polyamide stabilisers, such as, for example, copper salts incombination with iodides and/or phosphorus compounds and salts ofdivalent manganese.

7. Basic co-stabilisers, such as, for example, melamine, benzoguanamine,polyvinylpyrrolidone, dicyandiamide, triallyl-cyanurate, ureaderivatives, hydrazine derivatives, amines, polyamides, polyurethanes,and alkali metal salts and alkaline earth metal salts of higher fattyacids, for example Ca stearate, Zn stearate, Mg stearate, Na ricinoleateor K palmitate.

8. PVC stabilisers, such as, for example, organic tin compounds, organiclead compounds and barium-cadmium salts of fatty acids.

9. Nucleating agents, such as for example 4-tert.butylbenzoic acid,adipic acid and diphenylacetic acid.

10. Other additives, such as, for example, plasticisers, lubricants,emulsifiers, fillers, carbon black, asbestos, kaolin, talc, glassfibres, pigments, optical brighteners, flameproofing agents andantistatic agents.

The manufacture and use of the compounds according to the invention isdescribed in more detail in the examples which follow. In these, partsdenote parts by weight and % denote percentages by weight.

EXAMPLE 1

4.3 g (0.1 mol) of a 55-60% strength dispersion of NaH in toluene areadded to 17.2 g (0.1 mol) of2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptane in 200 ml of tolueneand the mixture is kept under reflux for 10 hours. A solution of 19.3 g(0.1 mol) of n-octyl bromide in 200 ml of dimethylformamide is thenadded dropwise and the mixture is kept under reflux for a further 12hours. It is cooled, the NaCl formed is filtered off, the filtrate isevaporated and the residue is distilled.4-Octyl-2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptane (I) of meltingpoint 134°C at 0.06 mm Hg is obtained.

EXAMPLES 2 - 6

The procedure is as in Example 1 except that, instead of the n-octylbromide used in that example, 0.1 mol in each case of the alkylatingagents given in column 1 of Table 1 is employed and the products listedin column 2 are obtained.

                                      Table 1                                     __________________________________________________________________________    Alkylation of 1,4-diaza-5-oxo-2,2,7,7-tetra-                                  methyl-cycloheptane with halogen compounds                                    Employed  Obtained product                                                                              Subst.                                                                             M.P.                                           halogen compound          No.  B.P.                                           __________________________________________________________________________    butyl bromide                                                                           4-butyl-2,2,7,7-tetra-                                                        methyl-1,4-diazo-5-oxo-                                                                       II  M.P./.sub.0.3 97°C                                 cycloheptane                                                        benzyl chloride                                                                         4-benzyl-2,2,7,7-tetra-                                                       methyl-1,4-diazo-5-oxo-                                                                       III M.P. 89°C                                          cycloheptane                                                        octadecyl bromide                                                                       4-octadecyl-2,2,7,7-tetra-                                                    methyl-1,4-diazo-5-oxo-                                                                       IV  M.P. <50°C                                         cycloheptane                                                        bromoacetic acid                                                                        4-methoxycarboxyl-                                                  methyl ester                                                                            methyl-2,2,7,7-tetra-                                                                         V   M.P. 100°C                                         methyl-1,4-diazo-5-oxo-                                                       cycloheptane                                                        0.05 mol of 1,4-                                                                        1,4-bis(2,2,7,7-tetramethyl-                                        dibromobutane                                                                           1,4-diaza-5-oxo-cycloheptyl-                                                                  VI  M.P. 148°C                                         4)-n-butane                                                         __________________________________________________________________________

EXAMPLE 7

A solution of 19 g of m-chloroperbenzoic acid in 200 ml of methylenechloride is added dropwise over the course of 3.5 hours to 15.5 g (0.55mol) of 4-octyl-2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptane in 100ml of methylene chloride. The reaction is slightly exothermic. Themixture is then stirred for a further 15 hours at room temperature andthe m-chlorobenzoic acid which has precipitated is filtered off. Thereddish-coloured methylene chloride solution is washed twice with 100 mlof 2 N sodium hydroxide solution at a time and then with 50 ml of 2 Nhydrochloric acid and is dried over sodium sulphate. After distillingoff the solvent, the residue is distilled in a high vacuum. 4-Octyl2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptan-1-oxyl (VII) of theformula ##EQU16## of boiling point 138°C at 0.02 mm Hg is obtained.

EXAMPLE 8

100 parts of polypropylene powder (Moplen, fibre grade, from Messrs.Montedison) are homogenised with 0.2 part ofβ-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid octadecyl ester asthe antioxidant and 0.25 part of a light stabilizer from Table 2 below,for 10 minutes in a Brabender plastograph at 200°C. The mass thusobtained is taken from the kneader as rapidly as possible and is pressedin a toggle press to give 2 - 3 mm thick sheets. A part of the pressedblank obtained is cut out and pressed between two high gloss hardaluminium foils for 6 minutes at 260°C and 12 tons pressure, using amanual hydraulic laboratory press, to give an 0.5 mm thick film which isimmediately chilled in cold water. The 0.1 mm thick test film isproduced from this 0.5 mm thick film under exactly the same conditions.Pieces of 60 × 44 mm are now punched from the 0.1 mm thick film andexposed in the Xenotest 150. At regular intervals of time, these testspecimens are taken from the light exposure apparatus and examined fortheir carbonyl content in an IR-spectrophotometer. The increase in thecarbonyl extinction during exposure to light is a measure of thephoto-oxidative degradation of the polymers [see L. Balaban et al., J.Polymer Sci. Part C, 22, 1059-1071 (1969); J. F. Heacock, J. PolymerSci. Part A-1, 22, 2921-34 (1969); D. J. Carlsson and DM. Wiles,Macromolecules 2, 587-606 (1969)] and is, according to experience,associated with a deterioration of the mechanical properties of thepolymer. Thus, for example, the film stabilised with antioxidant only iscompletely brittle when it reaches a carbonyl extinction of approx.0.300. The protective action of the light stabilizers according to theinvention can be seen from the following Table 2:

                  Table 2                                                         ______________________________________                                        Substance No.                                                                            Exposure time   CO-extinction                                                 hours, Xenotest 150                                                                           (5.82 μ)                                        ______________________________________                                        No light                                                                      protection 1,000           0.300                                              agent                                                                          I         6,000           <0.010                                              II        6,000           <0.010                                              VII       5,000           <0.010                                             ______________________________________                                    

EXAMPLE 9

100 parts of polystyrene granules are mixed dry with 0.25 part of alight stabilizer from Table 3 below and the mixture is regranulated inan extruder and subsequently moulded on an injection moulding machine togive 2 mm thick sheets. The sheets obtained are exposed for 2,000 hoursin the Xenotest 150 apparatus and their yellowing is determined asfollows, from the yellowing factor: ##EQU17## wherein Δ T is the loss intransmission at wavelengths 420 and 680 nm respectively, which hasoccurred during exposure, and T(560) denotes the transmission value inper cent of the unexposed sample at 560 nm. The results are shown inTable 3.

                  Table 3                                                         ______________________________________                                        Substance No.     T.F.                                                        ______________________________________                                        No light                                                                      stabilizer        20.0                                                         I                4.5                                                          VII              5.5                                                         ______________________________________                                    

EXAMPLE 10

100 Parts of polyethylene having a density of 0.917 are homogeneouslymixed in a Brabender plastograph with 0.1 and 0.3 parts, respectively,of a light-stabilising agent of formula I at 180°C for 10 minutes. Theresulting mixture is moulded in a platen press at 170°C to give 1 mmthick sheets, and these are examined visually for undissolvedconstituents. The sheets are suspended at room temperature, andperiodically examined for efflorescence phenomena. The results are givenin Table 4:

                  Table 4                                                         ______________________________________                                        Substance                                                                     No.          Solubility      Compatibility*                                   ______________________________________                                                   0.1%    0.3%      0.1%    0.3%                                     ______________________________________                                        2,2,7,7-tetra-                                                                methyl-5-oxo-1,4-                                                                          undissolved                                                                             undissolved                                            diazacycloheptane                                                              I           dissolved dissolved 200   200                                     II          "         "         200   200                                     III         "         "         200   200                                     IV          "         "         200   200                                    ______________________________________                                         *Compatibility: Number of days over which no efflorescence phenomena is       detectable.                                                              

I claim:
 1. A compound of the Formula ##EQU18## wherein R₁, R₂, R₃ andR₄ independently of one another are alkyl of 1 to 18 carbon atoms or R₁and R₂ and/or R₃ and R₄ together with the carbon atom to which they arebonded form a cyclopentyl, cyclohexyl or cyclooctyl ring, Y is hydrogenor the oxyl radical 0°, n is an integer from 1 to 4; and X, if n is 1,is alkyl of 1 to 20 carbon atoms; or an alkyl and/or alkylene containingsubstituent selected from hydroxyalkyl of 1 to 3 carbon atoms; --CH₂COOH; --CH₂ COOR₅ where R₅ is alkyl of 1 to 18 carbon atoms;--R₆ OOCR₇where R₆ is alkylene of 2 or 3 carbon atoms and R₇ is alkyl of 1 to 17carbon atoms; ##SPC5##wherein R₈ is alkylene of 2 or 3 carbon atoms andR₉ is tert.C₄ H₉ ; ##SPC6## --r₁₀ nhcor₁₁ where R₁₀ is alkylene of 2 or3 carbon atoms and R₁₁ is alkyl of 1 to 17 carbon atoms; --CH₂ CONH₂ ;--CH₂ CH₂ CONH₂ ; --R₁₂ CONHR₁₃ where R₁₂ is alkylene of 1 or 2 carbonatoms and R₁₃ is alkyl of 1 to 12 carbon atoms; --CH₂ CH₂ CONHC₆ H₅ ;--CH₂ CON(CH₃)₂ ; --CH₂ CN or --CH₂ CH₂ CN; --R₁₄ OR₁₅ where R₁₄ isalkylene of 1 or 2 carbon atoms and R₁₅ is alkyl of 4 to 8 carbon atoms;--R₁₆ SR₁₇ where R₁₆ is alkylene of 2 or 3 carbon atoms and R₁₇ is octylor phenyl; --CH₂ CH₂ SOR₁₈ where R₁₈ is octyl; --CH₂ CH₂ CH₂ SO₂ R₁₉where R₁₉ is dodecyl; --R₂₀ N(R₂₁) 2 where R₂₀ is alkylene of 2 or 3carbon atoms and R₂₁ is independently H or alkyl of 1 or 2 carbon atoms;and --CH₂ CH₂ NHCH₂ CH₂ CN; alkenyl with 3 to 18 carbon atoms;propargyl; benzyl; phenylethyl; phenylpropyl;3,5-di-tert-butyl-4-hydroxy-benzyl; 4-propionoxybenzyl; or4-ethoxycarbonylbenzyl; X, if n is 2, is alkylene of 1 to 18 carbonatoms; --(CH₂)₂ --O--(CH₂)₂ --; --(CH₂)₂ --S--(CH₂)₂ --; --CH₂ CH₂S--R₂₂ --S--CH₂ CH₂ -- where R₂₂ is alkylene of 2 to 12 carbon atoms;--(CH₂)_(p) ##EQU19## where p is 2 or 3 and R₂₃ is H, CH₃ ,C₂ H₅ or CH₂CH₂ CN; ##EQU20## where p is an integer from 1 to 3 and q is an integerfrom 2 to 12; ##EQU21## where R₂₄ is butylene; --CH₂ --O--CH₂ --, --CH₂--S--CH₂ -- or --(CH₂)₂ S(CH₂)₂ --; --(CH₂)_(p) CONH(CH₂)_(q)NHCO--(CH₂)_(p) -- where p is an integer from 1 to 3 and q is an integerfrom 2 to 12; --(CH₂)₂ --SO--(CH₂)₂ --;--CH₂ CH₂ --SO--(CH₂)_(q)--SO--CH₂ CH₂ -- where q is an integer from 2 to 12; ##EQU22## --CH₂--CH₂ SO₂ --CH₂ --CH₂ --; --CH₂ CH₂ --SO₂ --(CH₂)₆ --SO₂ --CH₂ CH₂ --;##EQU23## alkenylene or alkinylene with 4 to 6 carbon atoms;1,2-bis-(methylene)-benzene; 1,3-bis-(methylene)-benzene;1,4-bis-(methylene)-benzene; 1,2-bis-(ethylene) -benzene;1,3-bis,(ethylene)-benzene; 1,4-bis-(ethylene)-benzene; or4,4'-bis-(methylene)-diphenyl; X, if n is 3, is the group ##EQU24## inwhich m is a number from 1 to 2 and T is a saturated trivalent aliphatichydrocarbon radical with 3 to 7 carbon atoms; X, if n is 4, is ##EQU25##in which m is a number from 1 to 2 and Q is a saturated tetravalentaliphatic hydrocarbon radical with 4 or 5 carbon atoms; and its saltswith carboxylic acids or organophosphorus acids with 1 to 20 carbonatoms, phosphoric acid, hydrochloric acid, phosphorous acid or carbonicacid.
 2. A compound according to claim 1, wherein R₁, R₂,R.sub. 3 and R₄independently of one another are alkyl with 1 to 8 carbon atoms or R₁and R₂ and/or R₃ and R₄ together with the carbon atom to which they arebonded form a cyclopentyl or cyclohexyl ring, Y and n are as defined inclaim 1;X, if n is 1, is as defined in claim 1; X, if n is 2, isalkylene with 1 to 12 carbon atoms; an alkylene group of claim 1 whichhas ether, ester, thioether, amide, sulphoxide; sulphone or amino groupsand from 2 to 20 carbon atoms; alkenylene or alkinylene with 4 to 6carbon atoms; 1,2-bis-(methylene)-benzene; 1,3-bis-(methylene)-benzene;1,4-bis-(methylene)-benzene; 1,2-bis-(ethylene)-benzene;1,3-bis-(ethylene)-benzene; 1,4-bis-(ethylene)-benzene; or4,4'-bis-(methylene)-diphenyl; X, if n is 3, is the group of claim 1 inwhich T is as defined in claim 1 and m is a number from 1 to 2; and X,if n is 4, is the group of claim 1 in which Q is as defined in claim 1and m is a number from 1 to 2; and its salts with carboxylic acids ororganophosphorus acids with 1 to 20 carbon atoms.
 3. A compoundaccording to claim 1, wherein R₁ ,R₂ ,R₃ and R₄ are alkyl with 1 to 4carbon atoms or R₁ and R₂ and R₃ and R₄ together with the carbon atom towhich they are bonded form a cyclohexyl ring, Y and n are as defined inclaim 1;X, if n is 1, is alkyl with 1 to 18 carbon atoms or an alkyland/or alkylene containing substituent as defined in claim 1 which has 1to 18 carbon atoms; alkenyl with 3 to 5 carbon atoms; propargyl benzyl;3,5-di-tert-butyl-4-hydroxybenzyl; 4-propionoxybenzyl;4-ethoxycarbonylbenzyl; X, if n is 2, is alkylene of 1 to 8 carbonatoms; an alkylene group of claim 1 which has ether, ester, thioether,sulfoxide, sulphone or amino groups and from 2 to 12 carbon atoms;alkylene or alkinylene with 4 to 6 carbon atoms; or xylylene; X, if n is3, is the group of claim 1 in which T has 3 to 5 carbon atoms and m is anumber from 1 to 2; and X, if n is 4, is the group of claim 1 in which Qis as defined in claim 1 and m is a number from 1 to
 2. 4. A compoundaccording to claim 1, wherein R₁, R₂, R₃ and R₄ are methyl, Y is --H orthe oxyl radical--0°, n is the number 1 or 2; andX, if n is 1, is alkylwith 1 to 18 carbon atoms or an alkyl, and/or alkylene containingsubstituent as defined in claim 1 which has ester groups and from 1 to18 carbon atoms; allyl; methallyl, propargyl; or benzyl; and X, if n is2, is alkylene with 2 to 4 carbon atoms or an alkylene group of claim 1which has ester groups and from 6-10 carbon atoms.
 5. The compoundaccording to claim 1 which is4-octyl-2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptane.
 6. Thecompound according to claim 1 which is4-butyl-2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptane.
 7. Thecompound according to claim 1 which is4-benzyl-2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptane.
 8. Thecompound according to claim 1 which is4-methoxycarbonylmethyl-2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptane.9. The compound according to claim 1 which is1,4-bis-(2,2,7,7-tetramethyl-1,4-diaza-5-oxo-cycloheptyl-4)-n-butane.